1. Field of the Invention
The present invention relates to an absorbent composite, particularly to an absorbent composite which is useful in personal care products.
2. Description of the Related Art
Personal care products for the absorption of body fluids are known. Such products include adult incontinence products, diapers, training pants, feminine care products, wound dressings and the like. As a general rule, such personal care products generally comprise an amount of a cellulosic fiber such as wood pulp fluff. Wood pulp fluff is known to be a suitable absorbent for body fluids. As a general rule, 1 gram of wood pulp fluff is able to absorb from about 5 to about 8 grams of a discharged body fluid such as urine. A personal care product such as an infant diaper, generally has an absorbent capacity of at least about 200 to 400 grams of urine. Thus, when such an infant diaper is formed from wood pulp fluff, a relatively large quantity of wood pulp fluff must be employed.
In order to reduce the amount of wood pulp fluff and the corresponding bulk of such an infant diaper, it is known to include high absorbency materials known in the art as superabsorbents. Such high absorbency materials are generally capable of absorbing at least about 10, preferably at least about 20, and up to 50 or more times their weight in water. By incorporating such high absorbency materials in infant diapers, it is possible to reduce the overall bulk of the diaper while maintaining its absolute absorbent capacity.
Nonetheless, the use of such high absorbency materials is not without problems. For example, some high absorbency materials are known to cause gel blocking. That is, as the high absorbency materials become swollen with a liquid, they form a gelatinous mass which prevents the free flow of liquid therethrough. Thus, while the high absorbency materials may be able to absorb an initial insult, subsequent insults are unable to pass through the now swollen high absorbency material. As a result, subsequent insults tend to pool and run off of the absorbent product.
Accordingly, a number of different structures have been proposed to alleviate or reduce the problems associated with incorporating high absorbency materials in personal care products.
U.S. Pat. No. 4,699,619 issued Oct. 13, 1987, to Bernardin describes a multilayer absorbent composite having a first relatively low density layer and a second relatively high density layer underlying at least a portion of the first layer. A high absorbency material (superabsorbent) is described as being located between said first and second layers.
U.S. Pat. No. 4,102,340 issued Jul. 25, 1978, to Mesek et al. is directed to a disposable article with a particulate hydrophilic polymer in an absorbent bed. Described is an absorbent pad comprising a fibrous structure having an intermediate densified layer and a layer of highly porous, loosely compacted batt on both sides of the densified layer. One of the batt layers is described as including a particulate, water-insoluble but water-swellable polymeric absorbent.
U.S. Pat. No. 4,269,188 issued May 26, 1981, to Nishizawa et al. is directed to a disposable diaper. Disclosed is a disposable diaper including an absorbent material comprising a laminate wherein a water-absorbent polymer powder is fixed between two sheets of paper. A fluff pulp layer is located on both sides of the laminate containing a water-absorbing polymer.
While the structures described in the referenced patents have often proven beneficial, they have not completely solved the problems associated with the use of high-absorbency materials. In use, the wood pulp fluff generally serves to quickly absorb a discharged body fluid. The fluid is generally held in the pores of the fluff matrix. The high absorbency material in the fluff matrix then absorbs the fluid and, in effect, dewaters the fluff matrix. That is, the fluff serves to absorb and hold surges (relatively large quantities applied relatively quickly) of body fluid until the high-absorbency material can absorb the body fluid. Moreover, many known personal care products employ high-absorbency materials in relatively low quantities. This is because the cost of such high-absorbency materials is generally greater than the cost of a material such as wood pulp fluff. It is sometimes desirable to employ a relatively high concentration of high-absorbency material when forming a personal care product. As the concentration of high-absorbency material increases in an absorbent product, the concentration of wood pulp fluff generally decreases. The high-absorbency materials are not generally able to absorb urine at the rate at which it is applied. This may lead to leakage in absorbent structures having high concentrations of absorbent materials.
It is desired to provide an absorbent structure which may contain an absorbent layer having a relatively high concentration of high-absorbency material but which absorbent structure is capable of quickly absorbing body fluids applied thereto.